1. Field of the Invention
This invention relates to bladders used in tire building and is more particularly concerned with improved belt and tread transfer ring and drum expand bladders and with processes for the preparation thereof.
2. Description of the Prior Art
The fabric of fiber reinforcement of various types of bladder employed in tire building operations has been suggested in broad terms in the prior art. Illustrative of such prior art are Gostlin U.S. Pat. No. 1,378,172; Semler U.S. Pat. No. 1,910,128; Frolich et al. U.S. Pat. No. 2,305,412; Read U.S. Pat. No. 3,547,734; Nicholls et at U.S. Pat. No. 3,979,249; Schmit U.S. Pat. No. 3,990,930; Schichman et al U.S. Pat. No. 3,963,394 and Burley U.S. Pat. No. 4,249,979.
However, it has not previously been suggested that belt and tread transfer rings and belt and tread drum expand bladders could be reinforced using fabric, fibers and like reinforcing materials. Indeed, in view of the manner in which such rings and bladders have been prepared hitherto (by molding from extruded rubber sheet in closed molds), it is very difficult to devise any satisfactory method of introducing such reinforcement into these types of bladders.
It has now been found that the above types of bladders can be reinforced in a highly satisfactory manner by utilizing a novel process which will be described hereinafter. It has also been found that bladders prepared in accordance with this novel process exhibit markedly improved properties particularly in terms of the extended service life which they possess.